He raced to pick up the life jackets while his stepmother sent out a Mayday call.

他的继母发出无线电求救信号，他飞跑着去拿救生衣。

《柯林斯英汉双解大词典》

No other passenger jet in modern history had disappeared so completely — without a Mayday call or a witness or even a trace on radar.

因为，现代历史上还没有哪架客机像法航447航班一样消失如此彻底----没有求救信号，没有目击者，甚至没有在雷达上留下任何痕迹。

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A clearly worried Walters used his CB radio to transmit a mayday call, which was picked up by operators on the ground who then maintained contact with him throughout the flight.

Walters真的担心起来，他用无线电发了呼救信号，地面接线员接到信号并自此和他一直保持联系。

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Instructor Steven Lewis, 38, made a mayday call 20 minutes into the training flight from Blackpool Airport.

BBC: Mystery over Lancashire crash helicopter's mayday call

The Christos sent a Mayday call that was picked up by Brixham coastguards who have been co-ordinating the rescue.

BBC: Boat sinks after stricken tug crew rescued off Devon coast

Investigators have been unable to establish why a mayday call was made from a helicopter before it crashed in Lancashire, killing two people.

BBC: Mystery over Lancashire crash helicopter's mayday call